Some relevant tips if you're onboarding as an engineer in a smaller company:
Smaller companies will have less process and, therefore, a less formal onboarding. This means it's more important to get stuff done quickly since you can't rely on a bunch of classes or hand-holding.
A good benchmark is to land code within a week
In a smaller company, a lot of knowledge will be in the heads of a few people
Your goal is to find the tenured people and ensure you understand their worldview and prioritization.
Don’t assume processes or people exist. Especially if you come from a larger company, you should not assume that there is a well-defined QA (Quality Assurance) team or design team.